Sugar Crystals!

Broad Question

How do you grow sugar crystals?

Specific Question

Which chemical additive will cause the thickest sugar crust to grow on top of the water?

Variables

Independent Variable: Chemical Additive

Dependent Variable: Depth of the Sugar Crystal Crust Plate

Variables That Need To Be Controlled:

Amount of Sugar, Sitting time, String Length

Hypothesis

I predict that the corn syrup will grow the thickest sugar crust.

Graph of Hypothesis

Experimental Design

I plan to conduct an experiment involving which chemical additive will cause a simple sugar crystal concoction to grow the most crystals. I will do this at my house, most likely on my own, although I may get some assistance from my mother while boiling. I will be creating the crystals and measuring the depth in millimeters of each one after seven days of growing. I will print out a spreadsheet and write the numbers into it, so that way I wont forget the numbers and have to recount, and so I don’t risk breaking the crystals as I bring them to a computer. When I first make the sugar crystals, I will use the same amount of water and sugar for each one to make sure that is even. Then I will put the same number of whichever additive in each one, and put them in the same place for seven days to give a chance for the crystals to grow. I will take a picture of the crystals as I am counting them with a digital camera, which will document my experiment. After I record all of the data on the printed-out spreadsheet, I will transfer it onto my GoogleDocs and print it out at school. As for the pictures, I can print a couple of those at home and bring them into to put on my display board. I can put them on my Wikispace at home, along with my data.

Materials List

Sugar
Water
String
5 Pencils
Scissors
Oven
Pot
Jar
Cream of Tartar
Corn Syrup
Vinegar
Glycerin
Food Coloring
Ruler

Detailed Procedure

1. Gather materials.
2. Pour water into pot and boil.
3. While boiling, slowly add sugar until it stops dissolving in the water.
4. Pour the water/sugar mix into 5 separate jars. Put different color food coloring in each of the jars, and remember which has what colors.
5. In four of the jars, put either cream of tartar, corn syrup, vinegar, or glycerin and mix around.
6. Tie a piece of string to each pencil, and dangle one in each jar, resting the ends of the pencil on the edge of the jar.
7. Wait one week, then take the sugar crust off of the top of the water and measure the depth of the crystals.
8. Record your data in your data table.

Background Research

Growing sugar crystals is easy- if you know how. The process of sugar crystal growing is known as nucleation. You start out growing by making the solution that they will grow out of. Since water is the most common solvent, that is what you use to dissolve the sugar. When you mix sugar and water, the molecules mix together until they settle into an even mixture. You know the solution is finished when you add sugar and it no longer mixes into the concoction. When the crystals begin growing, they connect like legos locking together; except for instead of legos there are molecules. Watch out though, for some things can cause the sugar crystals to not grow at all, such as different types of sugar.
References
Helmenstine, Anne M. Grow Sugar Crystals- Make Your Own Rock Candy. Web. 8 Feb. 2012. http://chemistry.about.com/od/growingcrystals/ht/blsugarcrystal.htm.
The Science of Cooking. Exploratorium, n.d. Web. 8 Feb. 2012. http://www.exploratorium.edu/cooking/candy/sugar.html.
Growing Crystals. Howard Debeck Elementary School, n.d. Web. 8 Feb. 2012. http://nobel.scas.bcit.ca/debeck_pt/science/crystals/crystals_p1.htm.

Karpelenia, Jenny, ed. Mixtures and Solutions. Logan, IO: Perfect Learning Co., 2006. Print.

Results

Data Table

Type of Additive	Sugar Thickness (mm)
None	5
Corn Syrup	2
Glycerin	6
Vinegar	2
Cream of Tartar	4

Graphs

Photos

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Data Analysis

Conclusion

The original purpose of this experiment was to discover which chemical additive caused the most sugar crystals to grow on a string. The results of this experiment was actually measured in mm, and I measured how thick the sugar crust that was growing on top of the water was. It turned out that the glycerin had the thickest crust of 6mm, followed by the no-additive (5mm), the Cream of Tartar (4mm), and the vinegar and corn syrup (2mm).

Discussion

My hypothesis stated that corn syrup would grow the thickest sugar crust. However, my results did not support my hypothesis. There is no pattern between my independent and dependent variables. My data didn’t really show any trends, either.
My tests were anything but smooth. My initial project was going to consist of counting the number of crystals on each string, but after my first attempt there were simply no crystals growing. I used up over 5 lbs of sugar the second time, trying to get it to work properly. When I did that, I found that instead of growing on the string like they were supposed to, the crystals were growing on top of the water. I then devised a new plan for measuring the crystals, and was finally able to measure my data. If I could improve my experiment, I would have tried even more sugar (if possible) and tried multiple strings to see if that was the problem. An interesting future study may involve growing sugar crystals with different color food coloring in them.